Problem with sqlite3 and WAL

[peter]

I have a version of sqlite3 that is 3.7...

I have been having problems with the database being locked.

So I tried

    db.executesql("PRAGMA journal_mode=WAL;")

(just once)

I then cannot access the application without getting a 

OperationalError: unable to open database file

Any ideas how I can turn WAL on without this problem?

Things were otherwise working fine prior to trying to turn WAL on.

Thanks

[Ron Chatterjee]

Have you tried db.commit()?

[peter]

I have looked into it further, and two new files are created in my databases directory. 

storage.sqlite-wal

and

storage.sqlite-shm

They need their group write permissions to be set. However, they seem to keep on getting deleted and recreated. Each time they are created their group write permissions are not being set.

Anyone got any ideas on this.

Thanks for your suggestion Ron, I am not sure it is going to help here.

Peter

[peter]

Oh Ron, I see this might be a way of avoiding the lock problem without resorting to WAL. Thanks.

Peter

On Thursday, 28 January 2016 15:47:54 UTC, peter wrote:

[Ron Chatterjee]

I will make sure not to delete this post. lol. Cool. glad to help.

[peter]

I am restating my problem with all that I now know.

 

I have a version of sqlite3 that is 3.7...

I have been having problems with the database being locked.

So I tried

    db.executesql("PRAGMA journal_mode=WAL;")

(just once)

I then cannot access the application without getting a 

OperationalError: unable to open database file

If I look in the databases folder, I see that there are two file 

storage.sqlite-wal and 

storage.sqlite-shm

The first of these has 0 bytes as its size.

Both of them have the 'wrong' permissions in that they do not include group write permissions.

If I change the permissions of the two files, then reload the page, it works. 

However I will soon again get the 'unable to open database error', and the persmissions will need resetting.

Does anyone have any idea why I am getting these permission issues with the WAL file?

I set up a very simple application and WAL worked okay on that, so WAL is possible on my system.

If I turn WAL off and go back to DELETE everything works fine, but I am at risk of database locking. so I would prefer to be able to use Write Ahead Logging.

Thanks for any help

Peter

 

[Niphlod]

file permissions should be the issue because those files are not usual ones. 

[peter]

The strange thing is that it works okay with another app. So what I can I do about permissions. The permissions for the databases folder are okay. If I change the permissions on those files the changes are non persistent. So I am stuck.

[Dave S]

On Friday, January 29, 2016 at 7:34:57 AM UTC-8, peter wrote:

The strange thing is that it works okay with another app. So what I can I do about permissions. The permissions for the databases folder are okay. If I change the permissions on those files the changes are non persistent. So I am stuck.

You need to find out what's creating those files, and have it do the job correctly.

/dps

[peter]

I imagine it is sqlite3 itself that is creating them. How one can get it to change the way it does things I do not know. As I say it seems to work ok with another app that is in the same setup. So why sqlite should behave in an app specific way I do not know.

Peter